Linkage drive for windshield wipers



Aug. 1962 F. M. RYCK ET AL 3,048,045

LINKAGE DRIVE FOR WINDSHIELD WIPERS Filed Dec. 13, 1957 3 Sheets-Sheet 1INVENTORS FRANc/s M. Eyck BYHARR Y W ScHM/TZ ATTORNEY Aug. 7, 1962 F. M.RYCK ET AL LINKAGE DRIVE FOR WINDSHIELD WIPERS 3 Sheets-Sheet 2 FiledDec. 13, 1957 z s W Y R E m m MW v.1 mm M; E B

Aug. 7, 1962 F. M. RYCK ET AL 3,048,045

LINKAGE DRIVE FOR WINDSHIELD WIPERS Filed Dec. 13, 1957 3 Sheets-Sheet 3INVENTORS Francis M. Ryck BY Harry W Sohmitz nit This invention pertainsto the art of mechanical movements, and particularly to a drive linkageincluding angle multiplying transmission assemblies for windshieldwipers driven from rotary crank means.

It is well recognized that it is impossible to convert rotary motion ofa crank to oscillation of a pair of wiper shafts and obtain thetheoretically maximum angle of oscillation of the shafts with simplecrank and pitrnan arrangements in a motor vehicle wiper installation,due to manufacturing tolerances and the relative locations of the rotarycrank and the wiper pivot, or transmission, shafts In actual practice,oscillation throughout an angle of 90 is the most desirable from anengineering standpoint, although the angle of oscillation can beincreased to substantially 100 in some instances without reaching thedead center position of the linkage. However, if the configuration ofthe vehicle and the location of the pivot shafts is such that a wiperstroke of more than 100 is essential for adequate driver vision, someform of angle multiplying mechanism must be incorporated between thepivot shafts and the connecting links. Heretofore, it has been proposedto use gears having different pitch diameters atent for amplifying, ormultiplying, the angle of oscillation imparted to a wiper shaft toprevent movement of the linkage to its dead center position. Such anarrangement is shown in the Whitted Patent No. 2,053,861.

The present invention relates to linkage type angle multiplyingassemblies, and constitutes improvements over similar assembliesdisclosed in copending applications S.N. 674,495, Schmitz et al. filediuly 26, 1957, now Patent No. 3,010,136, and SN. 686,432, Schmitz et al.filed September 26, 1957, now Patent No. 2,977,623, and both assigned tothe assignee'of this invention, in that the effective length of thedrive arm does not vary so as, to vary the applied torque. Accordingly,among our objects are the provision of wiper drive linkage means forimparting asymmetrical oscillation to a pair of spaced wiper shafts froma single crank means and means for increasing the motion betweenconnecting links driven by a rotary crank and wiper shafts actuated bythe connecting links; the further provision of a link type anglemultiplying assembly designed to facilitate limited axial movement ofthe driven shaft; the further provision of a three element anglemultiplying linkage assembly wherein the connecting link connection andthe drive arm connection are substantially aligned; and the stillfurther provision of a four element linkage type angle multiplier.

The aforementioned and other objects are accomplished in the presentinvention by locating the wiper pivot shaft between a stub shaft and theend of a drive arm. Specifically, the angle multiplying linkageassemblies disclosed herein may be used with windshield wiper actuatingmechanism of the type set forth in the aforementioned application SN.686,432. However, reference to this type of actuating mechanism is onlyby way of example, and is not to be construed as a limitation.

In the disclosed embodiments, a pair of Wipers are oscillatedasymmetrically from a single crank means, that is a crank having aportion, or portions, extending on only one side of the rotary shaft. Toaccomplish this result, a motion reversing mechanism is incorporated onthe passengers side of the vehicle. Thus, the drive linkage for thepassengers side comprises a connecting link,

Fatented'Ang. '7, i952 "ice a reversing link, or bellcrank, and aconnecting arm, while the linkage for the drivers side merely includes aconnecting link.

The pivot shafts for oscillating the wipers are rotatably journalled inhousings suitably attached to the vehicle. In both linkage assemblyembodiments disclosed herein, the pivot shafts are capable of limitedaxial movement relative to the housings, which axial movement isimparted to the pivot shaft automatically during oscillation thereof bya cam and cam follower arrangement which may be of the general typeshown in Patent No. 2,806,557.

in the. first embodiment, the multiplying linkage comprises an idle arm,a drive arm, a supporting arm and a yoke type drive link. The idle armis connected at one end to a stub shaft rotatably journalled in the housing, the axis of the stub shaft being parallel to but spaced from theaxis of the pivot shaft. The drive arm is rigidly connected to the pivotshaft, and the support arm is rotatably journalled on a bushing carriedby the pivot shaft. The idle arm has a crank pin adapted for connectionat its other end to either the reciprocating connecting arm on thepassengers side, or the reciprocating connecting linkon the driversside. The idle arm and the supporting arm are interconnected by a yoketype drive link, one end of which is rotatably supported on the crankpin of the idle arm. The yoke has a crank pin attached to one legthereof, which crank pin extends through an aperture in the other legthereof and is rotatably journalled in the idle arm. The drive arm has abushing through which the crank pin of the yoke extends. Since the pivotshaft is disposed between the stub shaft and the endof the drive arm,reciprocation of the connecting arm on the passengers side, orconnecting link on the drivers side, will impart oscillation to the idlearm, and the drive arm will be driven by the drive link through an anglegreater than the angle of oscillation of the idle arm. The angle ofmultiplication is determined by the distance between the axis of thestub shaft and the pivot shaft.

In the preferred embodiment, the link type angle multiplier comprises atriangularly shaped idle arm, a drive arm and a drive link. The drivearm is attached to the pivot shaft rotatably journalled and slidablymounted in the housing. The idle arm is rigidly attached to a stub shaftjournalled in the housing and spaced from the pivot shaft. The idle armhas a ball stud extending from one side thereof and a pin extending fromthe other side thereof on the drivers side, and a pair of pins extendingin opposite directions on the passengers side. The connesting elementson the idle arms are located equal radial distances from the axis of thestub shaft. The connecting arm has a hub and a pin extending from oneside thereof, the hub of which slidably receives the pin on the idlearm, and the pin of which is slidably received by the drive arm. Theconnections between the idle arm and con necting link and/ or arm, andthe drive link and drive arm, are in substantial alignment. Since theaxes of the stub shaft and the pivot shaft are spaced apart, the angleof oscillation imparted to the drive arm will be greater than the angleof oscillation imparted to the idle arm. Moreover, the slidingconnection between the drive arm pin and the hub on the connecting linkpermits limited axial movement of the pivot shaft.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being bad to the accompanyingdrawings, wherein pre-- ferred embodiments of the present invention areclearly shown.

In the drawings:

FIGURE 1 is a schematic view of a windshield wiper 3,0 3 drive linkageconstructed according to one embodiment of this invention viewed frominside of a vehicle.

FIGURE 2 is a fragmentary view in elevation, depicting an anglemultiplying linkage assembly constructed.

according to one embodiment of this invention. I

FIGURE 3 is a fragmentary view, partly in section and partly inelevation, taken along line 33 of FIGURE 2. FIGURE 4 is a fragmentaryview, in elevation, of motion reversing mechanism associated with thepivot shaft assembly for the passengers side of the vehicle.

FIGURE 5 is a schematic view of a modified Windshield wiper drivelinkage viewed from the outside of the vehicle. FIGURE 6 is afragmentary view, partly in section and partly in elevation, taken alongline 6-6 of FIGURE 7. FIGURE 7 is a view partly in section and partly inelevation, illustrating a pivot shaft assembly having a preferred typeangle multiplying linkage.

With particular reference to FIGURE 1, a windshield Wiper drive linkageis depicted as being driven by an electric motor lil, the shaft of whichhas a worm 1i meshing 1- with a worm gear 12. The worm gear 12 carries asingle crank arm assembly 13 to which the inner ends of connecting linksM and 15 are rotatably connected. Structurally, the crank arm assembly13 may be of the type shown in Serial No. 686,432, aforementioned. Theouter end of connecting link 14 is rotatably connected to an idle arm 16having a fixed shaft, or stub shaft 18. The idle arm 16 is connected bya drive link 24 to a drive arm 22.. The drive arm is attached to a wiperpivot shaft 24, to which a wiper arm 25 for the drivers side, isconnected.

The outer end of the connecting link 15 is rotatably connected to oneend of a bellcrank 17 having a fixed intermediate pivot 19. The otherend of the bellcrank 17 is pivotally connected to a connecting arm 21,the connecting arm 21 also being pivotally connected to an idle arm 23for the passengers side of the vehicle. The idle arm 23 is attached to astub shaft 25, and is connected by a drive link with a drive arm 29. Thedrive arm 29 is rigidly attached to a wiper pivot shaft 31 which carriesa wiper arm 33 for the passengers side of the vehicle. A drivearrangement of this general type except for the specific anglemultiplying linkage assemblies is shown in the aforementioned copendingapplication Serial No. 686,432.

With particular reference to FIGURES 2 and 3, the angle multiplyinglinkage assembly for the drivers side of the vehicle is supported by atransmission housing, or bracket, 23 which is suitably attached to thevehicle. The stub shaft 12 is ro-tatably supported by a sleeve bearing34) within the housing 28, the stub shaft 13 being restrained againstaxial movement to the left, as viewed in FIGURE 3, by a snap ring, notshown. The stub shaft 18 islikewise restrained against axial movement tothe right, as viewed in FIGURE 3, by a bushing 32 interposed between theidle arm 16 and the sleeve bearing 34 As seen in FIGURE 3, the stubshaft I8 is riveted to the idle arm 16.

The wiper'pivot shaft 24 is likewise rotatably journalled in the housing23, but the shaft 24 is capable of axial movement relative to thehousing 28 in the directions of arrows 3 5. Wiper arm 26 is drivinglyconnected with the outer end of the pivot shaft 24, and the drive arm 22is rigidly connected to the inner end of the pivot shaft 24-.

- The pivot shaft 24 also supports a bushing 36, about which asupporting arm 38 is rotatably journalled. The axes of the shafts 18 and24 are parallel but spaced from each other as clearly shown in FIGURES 2and 3. Moreover, the pivot shaft 24 is located between the stub shaft 18and the drive link 2i) which interconnects the idle arm I6 and the drivearm 22 whereby any angular movement imparted to the idle arm 16 will beamplified and imparted to the drive arm 22 and pivot shaft 24. In otherwords, the radial distance between the wiper shaft 24 and the drive linkis less than the radial distance between the stub shaft 18 and the drivelink.

sense In the embodiment of FTGURES 2 and 3, the drive link is in theform of a yoke having arms 4b and 4-2 of different lengths. The longerleg, namely leg 4-2 is rotatably journalled on a bushing 44 carried by acrank pin 46 attached to the idle arm 1%. The shorter leg 4t; isapertured and receives a pin 4% riveted to the longer leg 42, andpassing through a bushing 5b carried by the support arm The pin alsoextends through a bushing, or bearing aperture, 52 carried by the drivearm 22. The reciprocable connecting link "ad is rotatably connected tothe pin 46 of the idle arm 16.

The sliding connection between the bushing 52 and the pin 48 permits thedrive arm 22 and the pivot shaft 24 to move axially in the direction ofarrow 34, the limits of movement being determined by engagement of thebushing 52 with the legs 49 and 42. of yoke type drive link 20. Axialmovement may be imparted to the shaft 24- by a cam and cam followerarrangement of the general type shown in the aforementioned Patent No.2,806,557. As will be apparent from an inspection of FIGURE 2, duringreciprocation of the link 14 which is rotatably connected to pin 46, theidle arm 16 will be oscillated throughout an angle indicated by X, whilethe drive arm 22 will be driven througth the drive link 2% throughout agreater angle, namely Y.

With reference to FIGURE 4, the transmission assembly associated withthe passengers side of the vehicle includes a motion reversing mechanismsince the crank assembly 13 extends on only one side of the axis of theworm gear 12, it is desired to oscillate the blades and armsasymmetrically, and there is insutficient space in the vehicle to havethe connecting link extend above the shaft 31 at the transmissionassembly. Accordingly, the passengers side of the transmission assemblyincludes a transmission housing, or bracket, 35. The bellcrank I7 isrotatably journalled on a fixed shaft 19 carried by the bracket 35. Theouter end of the connecting'link is rotatably connected to a pin, orball stud, 37 attached to the upper end of the bellcrank 17. Theconnecting arm 21 is rotatably connected to a pin 39 attached to theinner end of the bellcrank 17. The other end of the connecting arm Zllis connected to a pin 41 attached to the idle arm 23.

The idle arm, the drive arm, the support arm, and the yoke type drivelink associated with the passengers side of the vehicle are identicalwith like parts of the drivers side of the vehicle. Hence, the pivotshaft 31 is rotatably journalled in the bracket 35 and is capable oflimited axial movement relative thereto. The stub shaft is disposedabove the pivot shaft 31 and is restrained against axial movement. Theyoke type drive link 27 carries a pin 43 upon which the drive arm 29 isslidably mounted. Likewise, the pin 43 extends through 'a bushing in thesupport arm, not shown, for the passengers side transmission assembly.Accordingly, during reciprocation of outer surface of a windshield.

With particular reference to FIGURES 5 and 7, the preferred type ofangle multiplying linkage assembly will be described, wherein similarnumerals denote similar parts throughout the several views asaforedescribed. Thus, in the preferred system the connecting link 14 forthe drivers side is rotatably connected to a triangularly shaped idlearm attached to a stub shaft 18 on the drivers side. The wiper pivotshaft 24 is attached to the drive arm 22. The drive arm 22 and the idlearm 50 are connected by a drive link 52.

Similarly, on the passengers side, the connecting arm 21 is pivotallyconnected to triangularly shaped idle arm which the stub shaft 18 isjournalled by a sleeve bearing 30. The stub shaft 18 is restrainedagainst axial movement to the left as viewed in FIGURE 7 by a retainingring "54, and is restrained against axial movement to the right asviewed in FIGURE 7 by a bushing 32 which is confined by the idle arm 16and the housing 28. The pivot shaft 24 is rotatably journalled in thehousing 28 by spaced bushings, one of which 56 is shown in FIG- URE 7,and the other of which 72 is shown in FIGURE 6. The shaft 24 can slideaxially relative to the housing 28 in the direction of arrows 34,movement to the right being limited by engagement of a shoulder 24a onthe shaft with an internal shoulder 28a in the housing, and movement ofthe shaft 24 to the left being limited by engagement between the end ofa weather skirt 58 and the external shoulder 28b of the housing 28. Theweather skirt 58 slidably engages a reduced extension 28c of the housingin a telescopic manner, and is brazed, or otherwise suitably secured toa serrated drive burr 60 attached to the shaft 24. The drive arm 22 isrigidly attached to the inner end of the shaft 24. The idle arm 50 is oftriangular configuration as shown in FIGURE 6, and has a ball stud 62attached thereto and extending in one direction and a pin 64 extendingtherefrom in the other direction, these connecting elements being thesame radial distance from the axis of the stub shaft. The drive link 52has a hub 66' and a pin 68 extending from the same side thereof. The hub66 receives the pin 64, and the pin 68 extends through a bearingaperture 70 formed on the drive arm 22. The connection between the hub70 and the drive 22 and the pin 68 permits axial movement of the shaft24, as aforedescribed. The hub 68 is restrained against axial movementrelative to the pin 64 by snap ring 74.

As seen particularly in FIGURE 6, the connecting link 14 is connected tothe ball stud 62, the points of con-.

nection between the link 14 and the idle arm 50 being in substantialalignment with the connection between the drive link 52 and the drivearm 22. The reason for 10- cating these two points of connection insubstantial align. ment, or as close together as possible, is to reducethe distortion of the movement imparted to the drive arm 22 during.oscillation of the idle arm 50 by reciprocation of the connecting link14. As the connections between the idle arm 50 and the link 14 and thedrive arm 22 and the drive link 52 are displaced, the distortion, or inother words, the nonuniformity of angular velocity, of the drive armrelative to the idle arm increases.

The transmission assembly for the passengers side is identical to thatof the 'drivers side except for the fact that the idle arm 51 does nothave a ball stud thereon as does the idle arm 50. In place thereof, theidle arm 51 has a pin 55 to which the arm 21 is pivotally conis depictedin FIGURE 6, from which it can be seen that when the idle arm 50 isoscillated throughout an angle X by reciprocation of the connecting link14, the drive arm 22 and its shaft 24 will be oscillated through anangle Y, the angle Y being greater than the angle X. More over, byreason 'of having the pivotal connections between the link 14 and theidle arm 50, and the drive arm 22 and the drive link 52, in substantialalignment, the angular velocity of the drive arm 22 will besubstantially the same as the angular velocity of the idle arm 50.Moreover, since the crank assembly 13 is at its maximum throw positionat opposite 'ends of the stroke, the angular velocity of the idle arm 50and the drive arm 22 will automatically be a minimum at the stroke endsand a maximum at the middle of the stroke.

From the foregoing it is apparent that the present invention disclosessimple linkage arrangements for amplifying angular motion as derivedfrom a reciprocating closed constitute preferred forms, it is to beunderstood that other forms might be adopted.

What is claimed is as follows: i

l. A linkage drive for imparting asymmetrical oscillation to a pair ofspaced Wiper shafts from a rotary drive member having crank means ononly one side of the axis thereof, including, a pair of connecting linkshaving their inner ends rotatably connected to said crank means, a pairof spaced wiper shafts, a drive arm attached to each Wiper shaft, theouter end of one of said connecting links being operatively connectedwith one of said drive arms, a motion reversing link having a fixedintermediate pivotal support, the outerend of the other connecting linkbeing rotatably connected to one end of said reversing link, and an armoperatively interconnecting the other end of said reversing link andsaid other drive arm, whereby rotation of said crank means will impartasymmetrical oscillation to said wiper shafts.

2. A linkage drive for imparting asymmetrical oscillation to a pair ofspaced wiper shafts from a rotary drive member having crank means ononly one side of the axis thereof, including, a pair of connecting linkshaving their inner ends rotatably connected to said crank means, a pairof spaced Wiper shafts, a bracket for rotatably supporting each wipershaft, a stub shaft rotatably supported in each bracket, the axis of thestub shaft being parallel to but spaced from its respective wiper shaft,an idle' arm connected to each stub shaft, a drive arm connected to eachwiper shaft, a drive link pivotally interconnecting the respective idlearms and drive arms, the outer end of one of said connecting links beingpivotally connected to one of said idle arms, a bellcrank havingintermediate pivotal support in one of said brackets, the other end ofthe other connecting link being pivotally connected to one end of saidbellcrank, and a connecting arm pivotally interconnecting the other endof said bellcrank and said other idle arm whereby rotation of said crankmeans will impart asymmetrical oscillation to said idle arms, the radialdistance between each wiper shaft and its respective drive link beingless than the radial distance between each stub shaft and its respectivedrive link whereby oscillation of the idle arms throughout a stroke ofpredetermined amplitude will effect oscillation of said drive arms andsaid wiper shafts throughout a stroke of greater amplitude through saiddrive links, I

3. The linkage drive set forth in claim 2 wherein said wiper shafts areslidably sup-ported for axial movement relative to said brackets, andwherein the connection between each drive arm and its drive linkcomprises a pin on said drive link which extends through a bearingaperture of its drive arm.

4. The drive linkage set forth in claim 2 wherein the connectionsbetween the outer end of said one connecting link and its respectiveidle arm is in substantial alignment with the connection between thedrive link and its respective drive arm, and the connection between theconnecting arm and the other idle arm is in substantial alignment withthe connection between the other drive link and its respective drivearm.,

5. The drive linkage set forth in claim 2 wherein each wiper shaftrotatably, supports a supporting arm, and wherein each drive link is inthe form of a yoke, one leg of which is rotatably connected to itsrespective idle arm and the other leg of which is supported by a pinpassing through the bearing aperture of said drive arm and rotatablysupported in said support arm.

6. A movement amplifying transmission assembly for Windshield wipersincluding, a bracket, a wiper shaft rotatably supported in said bracket,a drive arm attached to said shaft, a stub shaft rotatably supported insaid bracket, the axis of 'said stub shaft being parallel to but spacedfrom the axis of said wiper shaft, an idle arm attached to said stubshaft, a support arm journalled for rotation about the axis of saidwiper shaft, and a drive link carried by said support arm and pivotallyconnected to said drive arm and said idle arm, the radial distance between the wiper shaft and the drive link being less than the radialdistance between said stub shaft and said drive link, wherebyoscillation of the idle arm throughout a stroke of predeterminedamplitude will effect oscillation of said drive arm and said wipe-rshaft throughout a stroke of greater amplitude.

7. The movement amplifying transmission assembly set forth in .claim 6wherein said drive link is in the form of a yoke, a pin attached to oneleg of the yoke and extending through the other leg thereof, said oneleg being pivotally connected to said idle arm, said pin being rotatablysupported in said support arm, and wherein said drive arm has a bearingaperture through which said pin extends.

8. The movement amplifyingtransmission assembly set forth in claim 7wherein said wiper shaft is supported for axial movement relative tosaid bracket,'.and wherein said pin is slidably received in the bearingaperture of said drive arm.

9. An angle multiplying linkage assembly including, a housing, an outputshaft'rotatably journalled in the hous ing, a stub shaft rotatablyjournalled in the housing, an idle arm connected to said stub shaft, adrive arm connected to said output shaft, a support arm rotatablysupported on said output shaft, and a drive link carried by said supportarm and pivotally connected to said idle and said drive arms, the radialdistance between said output shaft and said drive link being less thanthe radial distance between said stub shaft and said drive link wherebyoscillation of said idle arm will be multiplied and applied to saiddrive arm through said drive link.

10. The linkage assembly set forth in claim 9 wherein said drive linkis. in the form of a yoke having legs of different length, a pinattached to the longer leg, extending through an aperture in the shorterleg and rotatably supported in said support arm, the longer leg beingrotatably connected to said idle arm, the drive arm having a bearingaperture through which said pin extends.

ll. The linkage assembly set forth in claim 9 wherein said stub shaft isrestrained against axial movement while said output shaft is supportedfor axial movement relative to the housing, and wherein the pivotalconnection .between said drive link and said drive arm includes a pinattached to said drive link and slidably received in a bearing apertureof said drive arm.

12. A linkage drive for imparting asymmetrical oscillation to a pair ofspaced wiper shaft from a rotary drive ember having a crank arm assemblyextending from only one side of the axis of the said rotary drivemember, including, a pair of connecting links having their inner endsrotatably connected to said crank assembly, a pair of spaced wipershafts, a drive arm attached to each wiper shaft, the outer end of oneof said connecting links being operatively connected with one of saiddrive arms, a bellcrank having a fixed intermediate pivotal support, theouter end of the other connecting link being rotatably connected to oneend of said bellcrank, and an arm operatively interconnecting the otherend of said bellcrank and said other drive arm whereby rotation of saidcrankassembly will impart asymmetrical oscillation to said wiper shafts.

13. A linkage drive for imparting asymmetrical oscillation to a pair ofspaced wiper shafts from a rotary drive member having a crank assemblyextending from only one side of the axis of the drive member, including,a pair of connecting links having their inner ends rotatably connectedto said crank assembly, a pair of spaced wiper shafts, a bracket forrotatably supporting each wiper shaft, a stub shaft rotatably supportedin each bracket, the axis of the stub being parallel to but spaced fromits respective wiper shaft, an idle arm connected to each stub shaft, adrive arm connected to each wiper shaft, a drive link pivotallyinterconnecting the respective idle arms and drive arms, the outer endof one of said connecting links being pivotally connected to one of saididle arms, a reversing link having an intermediate pivotal support inone of said brackets, the other end of the other connecting link beingpivotally connected to one end of said reversing link, and a connectingarm pivotally interconnecting the other end of said reversing link andsaid other idle arm whereby rotation of said crank assembly will impartasymmetrical oscillation to said idle arms, the radial distance betweeneach wiper shaft and its respective drive link being less than theradial distance between each stub shaft and its respective drive linkwhereby oscillation of the idle arms throughout a stroke ofpredetermined amplitude will effect oscillation of said drive arms andsaid wiper shafts throughout a stroke of greater amplitude through saiddrive links.

14. A windshield wiper drive assembly comprising a bracket, a windshieldwiper drive shaft rotatably supported in said bracket, a drive armhaving one end secured to said shaft for pivotal movement of said drivearm about the axis of said shaft, an idle arm having an end pivotallyconnected to said bracket for pivotal movement of said idle arm relativeto said bracket, a drive link pivotally connected at one point thereonto the free end of said idle arm and pivotally connected at anotherpoint thereon to the free end of said drive arm, the distance betweenthe two pivot points of said drive link being less than the distancebetween the two pivot points of said idle arm and less than the distancebetween th two pivot points of said drive arm, and a member pivotallyconnected to said idle arm toward the free end thereof to impart to andfro motion to said idle arm relative to said bracket, the relativepositions of the idle arm-to-bracket pivotal connection, the idle arm-todrive linkpivotal connection and the idle arm-to-member pivotalconnection defining a triangle in the plane of to and fro moton of saididle arm, said triangle having two legs of substantially equal length,and the radial distance from the drive shaft to the drive link beingless than the radial distance from the pivotal connection of the idlearm with the bracket to the drive link whereby to and fro movement ofthe idle arm through a predetermined anglewill cause said drive arm andsaid drive shaft to be rotated to and fro through a greater angle.

15. A windshield wiper drive assembly as set forth in claim 14 whereinthe pivotal connection between said from the axis of said drive shaft,an idle arm having an end supported by said stub shaft for pivotalmovement of said idle arm about the axis of said stub shaft, a drive 9link pivotally connected at one point thereon to the free end of saididle arm and pivotally connected at another point thereon to the freeend of said drive arm, and a member pivotally connected to said idle armat the free end thereof to impart to and fro movement to said idle armrelative to said bracket, the two pivotal connections at the free end ofthe idle arm being spaced from each otherin the plane of the to and fromovement of the idle arm and being substantially the same radialdistance from the stub shaft, the radial distance from the drive shaftto the drive link being less than the radial distance from the stubshaft to the drive link whereby to and fro movement of the idle armthrough a predetermined angle will cause said drive arm and said driveshaft to be rotated to and fro through a greater angle.

References Cited in the file of this patent UNITED STATES PATENTS304,048 Tripp Aug. 26, 1884 2,395,768 Svoboda Feb. 26, 1946 2,594,085Smith Apr. 22, 1952 2,782,453 Schlage Feb. 26, 1957 2,895,158 RiesterJuly 21, 1959 FOREIGN PATENTS 716,825 Germany Jan. 30, 1942 1,013,136France Apr. 30, 1952

